The Pros and Cons of Tubular Daylighting Devices

By Torrin Greathouse | September 06, 2016

Over the year, various new designs have been innovated to improve on the traditional flat skylight design. Many of these have failed to get any traction in the market, but a few have managed to become industry mainstays. Tubular daylighting devices are on of these. Unlike traditional skylights, they use smaller rooftop domes to collect light and reflect it into the building through highly reflective, flexible light tubes. Here are a few of the pros and cons these daylights offer.

Pros

Reduces Energy Costs

Tubular skylights are more energy efficient than traditional skylights due to their unique design, but more importantly, they are far more well-insulated. One of the key issues traditional skylights face is that they generate a high level of heat loss and gain. The compact design on tubular systems on the other hand allows far less heat to transfer, minimizing excess HVAC usage.  

Produce More Light

Traditional skylights produces significantly less light than tubular devices of the same size. Tubular skylights maximize the light through the combination of transparent domes and reflective light tubes. During dawn and dusk, when the sun’s angle is low, the dome of  tubular daylighting devices capture sunlight more efficiently than traditional skylights and allows light to pass into the interior of a building.

Versatile Light Tubes

The key advantage of tubular daylighting devices is that they are applicable in situations where other skylights would not be able to function, such as when the space that needs illuminated is not a direct path from the roof. Their light tubes can be flexible and or can bend around HVAC ducts and other obstructions in the ceiling. Light tubes can be between 12 and 100 feet in length and are capable of passing through entire floors so lower floors can receive natural light as well as the top floor.

Cons

Number of Devices Required

When you are integrating a daylighting system it is extremely important to ensure that you are using the right amount of units for your facility. Tubular daylighting devices typically have an opening around 10-21 inches in diameter, while this compact design makes them easier to install, more devices are needed to sufficiently light a space. According to the NFRC tubular devices can require up to 5-10% of the space on a roof to provide adequate light. In large industrial constructions, this leads to installing a greater number of devices to illuminate the space.

Diminishing Light Intensity

Tubular daylighting devices can circumvent overhead piping or HVAC systems below the roof, even providing light to the lower stories of a building. However, any time light is reflected, a certain percentage is absorbed by the reflecting surface or scattered and diffused in many directions. Even if the light is coming in at an optimal angle, the newest and most advanced reflective materials still result in a 3% loss of intensity for every ten feet the light travels. While this does not seem like that much, it can rapidly add up, decreasing the efficiency of your system.

If you are not sure whether tubular daylights are the right system for you, consider downloading our eBook A Guide to Selecting the Best Skylight Solution for Commercial Buildings.
guide-to-selecting-the-best-skylight-solution

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